Systems and methods for direct air carbon dioxide capture

Abstract

A method for capturing and sequestering carbon dioxide (CO 2 ) includes receiving and performing an electrochemical process on the input liquid including water and a salt to produce at least one hydroxide-rich stream, and then capturing CO 2 from air using the hydroxide-rich stream and a passive air capture system, thereby producing a liquid carbonate solution containing air-captured CO 2 . Optional steps include disposing of the liquid carbonate solution, precipitating air-captured CO 2 from the liquid carbonate solution as solid carbonate and/or a slurry of carbonate, and mixing the liquid carbonate solution with a hydrogen-rich stream produced by the electrochemical process to generate gaseous CO 2 . Various integrations and synergies among CO 2 capture, renewable energy, water desalination, and metal and mineral extraction are provided.

What is claimed is: 
     
       1. A method for capturing and sequestering carbon dioxide (CO 2 ), comprising:
 receiving an input liquid comprising at least one of seawater, brackish water, and brine effluent; 
 performing an electrochemical process on the input liquid to produce at least one hydroxide-rich stream; 
 capturing CO 2  from air using the hydroxide-rich stream and a passive direct air capture system, thereby producing a liquid carbonate solution; 
 precipitating a solid carbonate and/or a slurry of carbonate from the liquid carbonate solution; 
 producing a hydrogen-rich stream at least in part with the electrochemical process; 
 dissolving a metal and/or a mineral into the hydrogen-rich stream to produce a metal and/or a mineral solution; 
 mixing the solid carbonate and/or the slurry of carbonate from the liquid carbonate solution with the metal and/or the mineral solution to produce a metal and/or a mineral carbonate mixture; 
 precipitating a metal and/or a mineral carbonate from the metal and/or the mineral carbonate mixture; and 
 recycling a salt solution from the metal and/or the mineral carbonate mixture by mixing the salt solution with the input liquid upstream from the electrochemical process. 
 
     
     
       2. The method of  claim 1 , further comprising pretreating the input liquid with the solid carbonate and/or the slurry of carbonate from the liquid carbonate solution. 
     
     
       3. The method of  claim 1 , further comprising processing the input liquid with a pretreatment stage before performing the electrochemical process, the pretreatment stage comprising one or more of a filtration system, a reverse osmosis concentration system, and an ion exchange system. 
     
     
       4. The method of  claim 1 , wherein performing the electrochemical process comprises performing electrodialysis with a bipolar membrane electrodialysis unit constructed and arranged to produce the at least one hydroxide-rich stream, the hydrogen-rich stream, and hydrogen gas. 
     
     
       5. The method of  claim 1 , wherein performing the electrochemical process comprises performing electrolysis to produce the at least one hydroxide-rich stream, hydrogen gas, and chlorine gas. 
     
     
       6. The method of  claim 5 , wherein producing the hydrogen-rich stream comprises combining the hydrogen gas and the chlorine gas to produce hydrochloric acid. 
     
     
       7. The method of  claim 1 , wherein the brine effluent comprises a desalination waste brine from a desalination facility.